/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hbase.regionserver.throttle;

import java.util.concurrent.atomic.AtomicInteger;

import org.apache.hadoop.hbase.regionserver.HStore;
import org.apache.yetus.audience.InterfaceAudience;

/**
 * Helper methods for throttling
 */
@InterfaceAudience.Private
public final class ThroughputControlUtil {
    private ThroughputControlUtil() {
    }

    private static final AtomicInteger NAME_COUNTER = new AtomicInteger(0);
    private static final String NAME_DELIMITER = "#";

    /**
     * Generate a name for throttling, to prevent name conflict when multiple IO operation running
     * parallel on the same store.
     * @param store the Store instance on which IO operation is happening
     * @param opName Name of the IO operation, e.g. "flush", "compaction", etc.
     * @return The name for throttling
     */
    public static String getNameForThrottling(HStore store, String opName) {
        int counter;
        for(; ; ) {
            counter = NAME_COUNTER.get();
            int next = counter == Integer.MAX_VALUE ? 0 : counter + 1;
            if(NAME_COUNTER.compareAndSet(counter, next)) {
                break;
            }
        }
        return store.getRegionInfo().getEncodedName() + NAME_DELIMITER + store.getColumnFamilyDescriptor()
                .getNameAsString() + NAME_DELIMITER + opName + NAME_DELIMITER + counter;
    }
}
